The present invention relates to a vehicle operation assist control system for assisting a vehicle operator to operate the vehicle according to map information and/or road information, and in particular to a vehicle operation assist control system which normally reduces the effort required for a vehicle operator to operate the vehicle but would not interfere with the vehicle operator taking an evasive action when necessary.
In recent years, various efforts have been made to reduce the efforts required for the vehicle operator to drive the vehicle. As a part of such efforts, various forms of intelligent transportation systems (ITS) have been proposed. An ITS typically collects information on the road which lies ahead of the vehicle so that the vehicle can travel along the road without the vehicle operator making any effort to operate the vehicle. Also, an ITS can prevent traffic accidents, and contributes to the reduction of emissions and other environmental problems by avoiding traffic congestions. Road information can be acquired by referring to map data incorporated in the system according to position data obtained from satellite navigation systems (GPS), radio wave beacons provided along the road, or induction cables buried under the road.
In an early stage of ITS development, a totally automated vehicle operation was sought as an application of a highly advanced form of artificial intelligence, and the expectation was high. Extraction of road boundaries by image recognition techniques and detection of obstacles by radars were examples of such efforts. Various developments have been achieved, but very few of them were considered to be applicable to practical situations. This owes to the fact that the technology for the recognition of environment has not been fully perfected as a practical and reliable system. For this reason, none of the intelligent transportation systems have been successfully put to practical use to the knowledge of the inventors.
For the intelligent transportation system to be reliable enough to be put to practical use, the inventors believe that the intervention of the vehicle occupant is indispensable. On the other hand, the intelligent transportation system is required to be able to minimize the mental and physical burden on the vehicle operator. Therefore, it is desirable to achieve a balance of authority between the vehicle operator and the system. In particular, when the vehicle encounters an obstacle which is not included in the traffic environment information, and the vehicle operator is required to take an evasive action on his/her own, the vehicle operator assist control system must not interfere the vehicle operator""s effort to take such an action.
In view of such problems of the prior art and the inventors""recognition, a primary object of the present invention is to provide a vehicle operation assist control system which can establish a balance of authority between the vehicle occupant and the control system.
A second object of the present invention is to provide a vehicle operation assist control system which enables the vehicle occupant to take an evasive action when necessary without being interfered by the control system.
A third object of the present invention is to provide a vehicle operation assist control system which gives a high priority to the vehicle operator"" intension but minimizes the effort, both physical and psychological, that is required for the vehicle operator to operate the vehicle.
According to the present invention, such objects can be accomplished by providing a vehicle operation assist control system for assisting a vehicle operator to operate a vehicle, comprising: map information means for providing map information of a road ahead of the vehicle; vehicle operation assist means for assisting the vehicle operator to operate the vehicle; and obstacle information acquiring means for acquiring information on an obstacle which lies ahead of the vehicle, said information including a distance to the obstacle and a width of the obstacle; the vehicle operation assist means being adapted to determine an evasion path, when an obstacle is detected by the obstacle information acquiring mean, and modifying the map information provided by the map information means, according to the distance to the obstacle and the width of the obstacle detected by the obstacle information acquiring means.
The obstacle information acquiring mean may consist of a radar using ultrasonic sound, electromagnetic radiation or a laser beam among other possibilities. The map information means may consist of an arrangement for storing map information and an arrangement for identifying the position of the vehicle such as a satellite navigation system (GPS), a beacon or other telecommunication path for receiving information on the position of the vehicle from a fixed station or an inductive cable buried under the road or provided along the road. The map information may also be downloaded from a fixed station. In any case, because the vehicle operation assist means takes into account the information on an obstacle, the control action of the system would not interfere with the vehicle operator when taking a necessary evasive action.
For the economy of computation, the evasive path may be defined as a curvature which changes as a sinusoidal mathematical function of the position of the vehicle along the path. The vehicle operation assist means may consist of a steering system which applies a certain steering torque so as to achieve a target vehicle side slip angle or yaw rate computed from the dynamic state of the vehicle in relation with the road, or may consist of a drive/brake force distribution system which distributes a drive/brake force between the right and left wheels of the vehicle, again, so as to achieve a target vehicle side slip angle or yaw rate computed from the dynamic state of the vehicle in relation with the road